SHARMA, I. M.ADIKSHITA2017-08-182017-08-182017http://krishikosh.egranth.ac.in/handle/1/5810028982ABSTRACT Mango anthracnose caused by Colletotrichum gloeosporioides Penz. with its perfect stage as Glomerella cingulata is one of the most prevalent and serious disease in all the mango growing regions of India including Himachal Pradesh. It causes significant fruit yield losses upto 60 per cent. Therefore, the present investigation was undertaken with the objectives to record the prevalence of this disease; study the variability of causal agent Colletotrichum isolates and evolve effective disease management strategy through the use of fungicides, botanicals, bio-agents and their combinations as well host resistance during the year 2014 - 2016. Mango anthracnose was recorded to occur in moderate to severe form in different mango growing areas of districts Kangra, Mandi, Sirmour and Solan of Himachal Pradesh. The mean disease incidence and per cent disease index varied between 40.6 to 77.19 and 23.02 to 63.98, respectively being highest at Jachh in district Kangra and lowest at Barotiwala in district Solan. Pathogenicity test revealed that symptoms appeared after 150 hours of incubation. Eleven isolates of Colletotrichum were isolated from mango and four isolates were isolated from apple, pomegranate and capsicum. These isolates differed in their ability to produced typical anthracnose symptoms w.r.t. incubation period (150-263 hours) and lesion size (35.67 to 75.44mm). Morphological and cultural studies indicated that these isolates varied in colony development (uniform, concentric rings, irregular), colour (white, grey, light- grey, orange, light-orange, yellowish-white) and diameter (5.5cm to 9cm), conidial shape (cylindrical, ovoid) and size (3.34 μm × 1.22μm to 17.36 μm × 2.70 μm), formation of acervuli (present/absent) on PDA and topography (raised fluffy and flat mycelium growth). Pathogen isolates also differed in exhibiting activity of pectin degrading enzymes (PG, PME), which corresponds to the lesion size produced by respective isolates on mango fruit being highest in mango isolate I4. Molecular phylogenetic analysis of DNA sequences clustered 10 isolates of Colletotrichum into two clades i.e. C. gloeosporioides and C. acutatum with NCBI blast databank sequences. RAPD and ISSR molecular markers differentiated the fifteen isolates on the basis of location, host, cultural and morphological characteristics. The protein profiling of eleven isolates of the mango anthracnose pathogen (C. gloeosporioides) resulted in the formation of three common protein bands of size 97 kDa, 70 kDa and 40 kDa. Screening of fifty one mango cvs. at RHR&TS-Jachh and Dhaulakuan revealed that only one cv. Pusa Pratibha behaved moderately resistant with PDI 13.16 on fruits other were either susceptible and highly susceptible. In vitro evaluation of twenty fungicides indicated that seven fungicides viz., difenoconazole, propiconazole, azoxystrobin, trifloxystrobin + tebuconazole, azoxystrobin + difenoconazole, azoxystrobin + tebuconazole, pyraclostrobin + boscalid were most effective and exhibited complete inhibition of mycelial growth of the pathogen. Evaluation of six IR chemicals under field conditions revealed that two consecutive spray of salicylic acid (0.075 %) at 20 days interval starting from the mid of August (16 August) was most effective (77.18% PDC). It also increased the level of total phenolic contents and activity of peroxidase, polyphenol oxidase and phenylalanine ammonia lyase enzymes to the maximum extent. In vitro evaluation of nine plant extracts revealed that leaf water extract of A.indica was most effective (MGI 74.2%) followed by fruit water extract of E.officinalis (MGI 62.47%). Amongst 21 bio-control agents evaluated under in vitro conditions three namely T. harzianum, T. viride and T.hamatum were highly effective (MGI 88.52 - 89.26%). Evaluation of effective fungicides, as fruit dip under laboratory conditions as well as under field conditions by giving three consecutive sprays starting with the first appearance of disease followed by two spray at an interval of 15 days for two consecutive year 2015 and 2016 revealed that fungicide Nativo (trifloxystrobin + tebuconazole) (0.04%) was most effective under lab conditions with DRI 89.08 per cent and also under field conditions with maximum disease control on leaves (88.65%) and fruits (88.05%). Similarly, among plant extracts, leaf water extract of A.indica (15%) provided maximum DRI on mango fruit upto an extent of 74.82 per cent as fruit dip under lab conditions and mean disease control to the tune of 53.28 and 50.20 per cent on leaves and fruits, respectively, under field conditions. Among six effective BCA’s, T.harzianum isolate 1 (5%) (1.2x104cfu/ml) was most effective (DRI 81.67 %) under lab conditions and also gave highest mean disease control on leaves (57.34%) and fruits (54.62%) under field conditions. In compatibility studies of effective fungicides, botanicals and bio-control agents it was observed that azoxystrobin was compatible with the T. harzianum, T. virens, Bacillus subtilis and P. flourescens whereas, trifloxystrobin + tebuconazole (Nativo) was compatible with B. subtilis and P. flourescens.` Under IDM studies, fruit dip in a combined treatment of Nativo (0.03%) + Bacillus subtilis (5%) for 5 minutes was most effective (93.39% DRI) and it was followed by combined treatment of Nativo (0.03%) + P.fluorescens (5%), difenoconazole (0.012%) + P.fluorescens (5%) and azoxystrobin (0.04%) + P. anomala (5%) with DRI varying between 87.08- 91.72 per cent.ennullThesis